Voltage-to-frequency converters in the form of integrated circuit components are known, which require input voltages in the order of volts. The conversion is effected with an accuracy of approximately 0.8 percent of the end value over the range of operating temperatures. This accuracy is achieved only, if each individual converter component of each computer or sensor, respectively, is manually adjusted with respect to offset of characteristic and gain. The accuracy of the conversion is heavily affected by variations of the ambient temperature due to the influence thereof on the characterizing parameters of the components.
Often, however, sensors provide signals in the range of millivolts. In order to permit processing of such signals with a commercially available voltage-to-frequency converter, the signals have to be pre-amplified. Such pre-amplification is effected by means of an operational amplifier. This operational amplifier, however, introduces errors of the signal to be converted due to offset of characteristic, gain variations and its dependence on temperature.